I doubt that it will have a tremendous impact, although I don't doubt that it will have at least some impact, especially if we see a Blu-ray player that also supports DVD-A/SACD. It provides an ideal upgrade path for retaining perfectly good processors, but there's also a huge and almost irrational desire for HDMI v1.3 in the marketplace. I saw more than one thread at AVS asking why we didn't have HDMI v1.3 receivers yet six months before the specs for HDMI v1.3 were published - that mindset is still powerful, and will continue to drive upgrades. Players like the BD50, on the other hand, can provide an alternative for folks who plan to keep existing hardware.
There are certain reasons that I could use to justify an upgrade to my trusty 990. Having unified video processing to allow all inputs to go to a single input on the TV, for example, would be a nice feature for ease of system use. Room EQ systems like Audyssey and Trinnov may have some appeal, but by themselves I don't find them sufficient to sway me. Having HDMI presents both convenience (less cabling, for example) and headaches (HDCP, for example).